1. Field of the Invention
The present invention relates to a locking mechanism adapted for use in a seatbelt system for protecting an occupant in an emergency situation of a vehicle and more particularly to a locking mechanism adapted for use in a webbing retractor winding an occupant-restraining webbing and, in the emergency situation, stopping an webbing-unwinding motion of the webbing retractor.
2. Description of the Prior Art
The webbing retractor is such constructed that the occupant-restraining webbing is wound on to a webbing takeup shaft and the locking mechanism is worked to stop a webbing-unwinding rotation of the takeup shaft in the emergency situation so that the occupant is put in his restrained situation.
The locking mechanism is constructed in such a manner that a lock plate is rotated together with the takeup shaft and is moved outwardly in a tangential direction of the takeup shaft to be caused to engage with an internal gear ratchet wheel, whereby the webbing retractor can be made small-sized.
Also, a plurality of lock plates can be arranged centering around the axial center of the takeup shaft, whereby it is expected that the webbing-unwinding rotation of the takeup shaft is stopped securely.
However, in case that the plurality of lock plates are disposed about the takeup shaft, it is difficult due to tolerance in manufacture or the like that each of the teeth portions of the respective lock plates moved outwardly in tangential directions of the takeup shaft in the emergency situation comes surely into mesh with the internal gear ratchet wheel at its predetermined position. Accordingly, a mechanism causing the teeth portions of every lock plates to engage with the internal gear ratchet wheel has been expected in this field.